I know I quote him often, but he keeps publishing awesome content, what else am I going to do? From Seth Godin:
Before you design a chart or infographic
What's it for?
A graph only exists to make a point. Its purpose is not to present all the information. Its purpose is not to be pretty.
Most of all, its purpose is not, "well, they told me I needed to put a graph here."
The purpose of a graph is to get someone to say "a-ha" and to see something the way you do.
Begin there and work backwards.